Dating : My [24m] interest in a friends [21f] sister

Dating : My [24m] interest in a friends [21f] sister

Short story:
Became super close with friend at work. Boned said friend. She got back together with ex, nothing more than close friends now. Mentioned multiple times how her sister and I would hit it off. Now can’t stop thinking of sister, and want to talk to her/make contact, but have been strongly advised against it. What should I do?

Long story:
I [24m] recently (4 months ago) got in touch with a girl [21f] at work and we initially hit it off as really good friends. We talked every day etc and became closer with her, she also had a partner at the time. As time went on she had a huge blow up with him and they officially broke up. During that time we started staying together and had a brief (3 week) stint where we were seeing each other, but came to an end when she got back with her partner. During that time there was a shit storm on whether she’d go back to him or stay with me, as we are both really close.

Ultimately she stayed with him, and we’ve stayed super close as friends still, but we both (rarely) talk about ending up together if they don’t work out (weird I know).

I know in this case I’m the back up, and literally whenever they fight she calls me/runs to me, but recently came to the conclusion she’s gonna stay with him regardless, which I’m all for (shit got crazy).

During this time though, she mentioned multiple times how perfect a match I’d be for her sister (22f), and that our personalities/interests are almost the exact same. As my interest subsided in her and we’ve settled on friends, I’ve noticed more and more that I’m always thinking of her sister and wondering what could happen.

So I bit the bullet and asked her about her sister, to which she laughed and said to « try and talk to her and see what happens ». She then said after that if I tried they’d end up talking about me and she’d tell her not to talk to me, then they’d both block me.

However, I know there is still a little bit between us, and still talks about us possibly ending up together, so I have the thought it’d upset her and she’d sabotage it.

But I can’t stop thinking of her sister, and feel like I’m missing such a huge chance, and I came here to see what suggestions everyone would have in regard to what I should do regarding the whole situation. Help pls.